不同类型生物活性滤床对诺氟沙星的去除

诺氟沙星作为一种抗生素广泛应用于人类日常生活,并大量进入水体环境,给水环境质量和生态系统安全带来隐患。研究了由3种不同填料组成的水平流和复合垂直流生物活性滤床对诺氟沙星的去除效果,结果表明,在水力负荷为0．1m^3／（m^2·d）、进水诺氟沙星浓度为392．11—686．17μg／L（平均浓度为500．97μg／L）条件下,复合垂直流滤床对诺氟沙星去除效果普遍好于水平潜流滤床,以沸石为填料的复合垂直流生物活性滤床对诺氟沙星的去除效果最好,平均去除率为80．61％,说明选择合适填料和合适类型的生物活性滤床可以作为去除诺氟沙星的一种有效方法。     

Impact of dissolved organic matter on the photolysis of the ionizable antibiotic norfloxacin

Norfloxacin (NOR), an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ubiquity. Therefore, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter (DOM), which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance (EPR) were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical (·OH) and singlet oxygen (¹O₂) based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of UOH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and ¹O₂. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored.     

Photodegradation of Norfloxacin in aqueous solution containing algae

Photodegradation of Norfloxacin in aqueous solution containing algae under a medium pressure mercury lamp (15 W, λ_max = 365 nm) was investigated. Results indicated that the photodegradation of Norfloxacin could be induced by the algae in the heterogeneous algaewater systems. The photodegradation rate of Norfloxacin increased with increasing algae concentration, and was greatly influenced by the temperature and pH of solution. Meanwhile, the cooperation action of algae and Fe(III), and the ultrasound were beneficial to photodegradation of Norfloxacin. The degradation kinetics of Norfloxacin was found to follow the pseudo zero-order reaction in the suspension of algae. In addition, we discussed the photodegradation mechanism of Norfloxacin in the suspension of algae. This work will be helpful for understanding the photochemical degradation of antibiotics in aqueous environment in the presence of algae, for providing a new method to deal with antibiotics pollution.     

阳离子强度和阳离子类型对诺氟沙星土壤吸附的影响

以OECD Guideline 106为基础,采用批平衡方法研究不同Ca²⁺离子强度（0.01、0.03、0.05、0.08和0.10 mol/L的CaCl₂溶液）和不同阳离子（0.01 mol/L的NaCl、KCl、NH₄Cl、MgCl₂、CaCl₂、ZnCl₂和AlCl₃溶液）对诺氟沙星在4种土壤（潮土、黄棕壤、水稻土和红壤）中的吸附-解吸影响.结果表明,随着溶液中Ca²⁺离子浓度的增加,诺氟沙星在土壤中的吸附参数K_f值逐渐减小并趋于稳定,两者间存在显著负相关（p≤0.05）.同时,Ca²⁺离子浓度的增加对低浓度诺氟沙星溶液的吸附影响相对高浓度而言不明显. 低pH下,诺氟沙星主要以阳离子形态存在,吸附以阳离子吸附或氢键为主;在兼性离子状态时,则主要以静电吸附和偶极力为主.这是造成4种土壤中诺氟沙星吸附差异的根本原因.在不同离子强度下,土壤溶液中二价Ca²⁺离子存在则对诺氟沙星的活性吸附位点造成竞争性吸附,从而降低诺氟沙星的土壤吸附量.同时,不同阳离子导致诺氟沙星的土壤吸附存在差异.其影响趋势主要为价态的影响,即价态越高,竞争吸附能力越强：M⁺（Na⁺、K⁺、NH^＋₄）2+（Ca²⁺、Mg²⁺、Zn²⁺）3+（Al³⁺）.     

诺氟沙星(Norfloxacin)对蛋白核小球藻(Chlorella pyrenoidosa)生长及抗氧化酶活性的影响

以蛋白核小球藻(Chlorella pyrenoidosa)为实验材料,研究了喹诺酮类药物诺氟沙星(Norfloxacin,NFLX)对小球藻生长及抗氧化酶活性的影响.结果表明,NFLX对小球藻的96hEC50为30.78mg·L-1,属于低毒.NFLX暴露对小球藻谷胱甘肽硫转移酶(GST)和过氧化氢酶(CAT)具有显著影响,当NFLX浓度高于30mg·L-1时,小球藻GST活性受到显著诱导,并随NFLX浓度增加而显著升高,而小球藻CAT活性随NFLX暴露浓度的升高表现出先诱导后抑制现象.NFLX对谷胱甘肽(GSH)和7-乙氧基-异吩唑酮-脱乙基酶(EROD)的影响较弱.在低浓度NFLX暴露下,GST和CAT可作为NFLX暴露的生物标记物.